<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script>
    {
        // 1
        function fn(){

        }
    }
    {
        // 2
        const fn = function(){

        }
    }
    {
        // 3
        setTimeout(function(){

        })
    }
    {
        // 4
        const fn = new Function("a","b","return a+b");
        console.log(fn(1,2))
    }
</script>
</html>